Grinding mill



Aug. 27, 1935. E. BAILEY 1-:1' AL 2,012,266

' GRINDING MILL Original Filed July 25, 1929 4 Sheets-Sheet l .,*N I 6p E l vul' MMM? i INVENToRs y ATTORNEYS Aug. 27, 1935.

GRINDING MILL original Filed July 25, 1929 4 Sheets-Sheet 2 E. G. BAILEY Er AL 2,012,266 Q Aug. 27, 1935.

E. G. BAILEY El' AL GRINDING MILL Original Filed July 25, 1929 4 Sheets-Sheet 3 F1G5. M@

Aug. 27, 1935. E G, BA|LE`Y ET AL 2,012,266

GRINDING MILL Original Filed July 25, 1929 4 Sheets-Sheet 4 ATTOR EYJ Patented Aeg. 27, 1935 UNITED'- STATES PATENT OFFICE GRINDING MILL Application July 25, 1929, Serial No. 380,865 Renewed July 25, 1934 26 Claims.

This invention relates to a grinding mill that is especially useful in connection with grinding or pulverizing coal, but is not restricted to this particular use. In carrying out the invention, the material to be ground is caused to pass through rows of grinding balls, and the fine particles of ground material are picked up by means of a current of air that passes between the rows of balls and carries the ne particles away from the mill.` 1

'I'he invention will be understood from the description in connection with the accompanying drawings, in which Fig. 1 is a vertical section through an illustrative embodiment of the invention; Fig. 2 is a plan view taken along the line 2 2 of Fig. 1; Fig. 3 is a section taken along the line 3 3 of Fig. 1; Fig. 4 is a section taken along the'line 4 4 of Fig. 1; Fig. 5 is a section taken along the'line 5 5 of Fig. 1; Fig. 6 is a vertical section through one. of the parts on an enlarged scale, and'Fig. '7 is a section taken along the line 1 1 of Fig. 6. A l l In the drawings,vreference character I indicates a support upon which the base 2 of the mill is supported, being attached to the support by means of the bolts 3. A driving shaft 4 extends through a hole or opening provided in the base 2, and is driven by means of a motor 5.through reduction gearing 6.

A grinding ring 1 is located upon the base 2 and is supported thereby in a stationary position. A driving disc or member 8 is attached to the shaft 4 and is provided with an upwardlyextending flange 9 and a downwardly .extending flange I0, these flanges providing a revoluble cylinder.

A stationary ring II is mounted upon the base 2 immediately below the flange I0 in such a position that the upper edge of the ring II lies in close proximity to the lower edge of the flangeA I0. The outside surface of the ange I is near the inner surface of the ring 1, so that a narrow annular space I2 is provided for the passage of air between the iiange and ring.

The grinding mill is provided with a wall I3 lcylindrical in cross section, which extends upwardly from the base 2. A wind box I4 is provided around the lower portion of the wall I3 and may be supplied with air under pressure from any convenient source, not shown.' A sheet metal plate I5 in the form of a truncated cone extends from the lower portion of the `ring 1 outwardly to the inside of the wall I3 some distance above the lower side of the wind box I4. A space is left outside of the ring 1 in which scrap iron or the like may be caught. Openings I6 are provided tained upon from the wind box I 4 into the space below the plate I5. Curved ports I1 lead from this space through a flange I1 on the base 2 into the annular space I2.

One or more vertical recesses I8 (Fig. 4) are provided in the flange 9, and corresponding lugs I9 are provided upon a driving ring or table 20 which extend into the recesses I8. The driving ring or table has grinding ball grooves along its upper and lower faces, and a plate 2lV that may be made in two sections for convenience of removal covers the opening in the ring 20. Ports 22 (Figs. 1 and .4) are provided through the ring 20 between its upper and lower edges to connect the upper portion of the space I2 to the space above the plate I5.

A row of grinding balls 23 is located between the ring 1 and the lower edge of the ring 20, and a row of grinding balls 24, each ball preferably larger than the balls 23, is located between the upper face of the ring 20 and an upper stationary grinding ring 25 provided with a ball groove along its -lower face.

A pressure ring 26 is located upon the grinding ring 25, and an annular plate 21 extends from the ring 26 with an inwardly turned iiange whose edge extends close to the outside upper edge of the ring 20 leaving an annular space 21 for the passage of particles partially ground. The arrangement of the plate 21 relative to the grinding ring 20 provides a restriction controlling the flow of material between the upper and lower grinding stages, which is disclosed and genericallyA claimed in our copending application Serial No. 390,698,

filed September 6, 1929., Lugs 28 are provided.

along the upper side'of the ring 26 upon which the lower ends of spring-pressed rods 29 rest.

The rods 29 arepressed downwardly by. springs 3U, so that increased grinding pressure, is obthe grinding balls when the feed of material is suiiiciently great to cause thering -26 to rise. The springs 30 for each rod 29 are housed in a housing 3| with their upper ends pressed against the upper end of the housing.

A hand wheel 32 is provided upon a shaft that has a worm screw 33 meshing with a gear 34upon an internally threaded sleeve 35 which is, in turn, mounted upon theY externally threaded housing 3|. A washer 31 is provided upon the rod 29 and rests against a shoulder thereon, with the lower ends of the springs 30 pressed against this washer. A stop 36 is provided on the rod 29 to con-v tact with the upper end of the housing 3| to limit the downward travel of the rod 29, so that the cies springs will not exert pressure upon the ring 26 at light loads.

A feed'spout 39 is provided through the upper portion of the wall I3 of the mill, and an outlet 40 is provided at the upper end of the mill. A conical separator 4| having its lower end 42 open is located below the outlet 40, with its upper edge extending higher than the lower edge of the outlet 40.

The operation is as follows:

The mill is set in motion, and air under pressure is introduced into the wind box I4. Material to be ground is fed through the spout 39 onto the cover 2| into the space within the row of balls 24, and the material is partially ground by the balls as it passes outwardly in a substantially radial direction. When the particles have been reduced suiciently in size, they drop downwardly through the annular space 21 into the space above the annular plate |5 and thence inwardly and substantially radially through the row of balls 23 where the particles are finely ground. 'The air from the wind box I4 passing through the ports l1 into the narrow annular space |2, rises with suiliciently high velocity to pick up the fine particles of material along the inner edges of the row of balls 23 and carries the material out through the ports 22. The revolution of the ring 2U causes the ports 22 to produce a suction A or fan-like action to aid the air and fine particles to rise and pass through the ports 22. The mixture of air and fine particles leaving the ports 22 passes through the material that is falling downwardly through the annular space 21 and picks up the fine particles therefrom.

The area of the air path, after it leaves the ports 22, increases in size above the plate I5, thus lowering its velocityand permitting the larger particles to fall downwardly and be ground again by the balls 23. The mixture of air and ne particles passes over the upper edge of the separator 4| and under the lower edge of the outlet 40`, thus changing suddenly in direction and giving further opportunity for large particles to separate and pass downwardly through the opening 42 and be ground further while the air and iine particles pass out through the outlet 40.

While in accordance with the provisions of the statutes we have illustrated and described herein the best form of our invention known to us, those skilled in the art will understand that changes may be made in the form of the apparatus and character of the carrier medium disclosed without departing from the spirit of the invention covered by our claims, and that certain features of our invention`may sometimes be used without a corresponding use of other features.

In our claims, the term air is used generically to cover any gaseous carrier medium suitable `for removing pulverized material in the manner described.

We claim: 1. In a rolling grinding mill, two rows of grinding elements one above the other, a driving ring' between said rows, said ring having ports therethrough, and means for passing ground material outwardly through said ports.

2. In a rolling grinding mill, two rows of grindbetween said rows, said ring 4having ports therethrough, and means for passing material to be ground through said rows of elements and theA ground material outwardly through said ports.

3. In a rolling grinding mill, two rows of grinding elements one above the other, a driving ring near the outside of the upper row of elements.

4. In a rolling grinding mill, two rows of grinding elements one above the other, a driving ring between said rows, and means for passing air upwards at high velocity along the inside of the lower row of elements in close' proximity to said balls and then between said rows.

5. In a rolling grinding mill, two rows of grinding elements one above the other, a driving ring between said rows, said ring having ports therethrough, and means for passing material to be ground through said upper row of elements from the inside of said row and through said lower row from the outside thereof and returning ground material between said rows.

6. The process of grinding material which comprises giving said material a preliminary grinding at one place, passing it to another place and further grinding it, and picking up the material in a current of air passing upwardly and then passing it with the air through the material as it passes from the preliminary grinding place to the place of further grinding.

7. The process of grinding material which comprises giving said material a preliminary grinding at one place, passing it to another place and further grinding it, picking up the material in a current of air passing upwardly and then passing it with the air through the material as it passes from the preliminary grinding place to the place of further grinding, and lowering the velocity to prevent undesirably large particles from being carried away between the two grinding operations.

8. In the process of grinding material,.the steps which comprise passing the material outwardly through a circular grinding zone while grinding it', then inwardly through another circular grinding zone while grinding it more, and passing a current of air outwardly through the material as it passes from one zone to the other.

9. In a grinding mill, grinding elements, and a rotatable grinding ring for said elements having radially disposed openings therethrough whereby a fan action is caused to aid in carrying away ground material when said ring is rotated.

10. In a rolling grinding mill, two rows oi.'

grinding elements one above the other, a driving v ring between said rows, said ring having ports therethrough,l means for causing air to carry ne particles outwardly through said ports, and adjustable means to regulate the passage of material from the upper to the lower row of elements.

11. In a rolling grinding mill, two rows of grinding elements one above the other, a driving ring between said rows, means for passing air upwards at high velocity along the inside of the lower row of elements in close proximity to said elements and then between said rows, and adjustable means to regulate the passage of material from the upper to the lower row of elements.

l2. In a rolling grinding mill, two rows of grinding elements one above the other, a driving ring between said rows, said ring having ports therethrough, means for passing material to be ground through said upper row of elements from the inside of said row and through said lower row from the outside thereof and returning ground material between said rows, and adjustable means to regulate the passage of material from the upper to the lower row of elements.

13. In an air-swept grinding mill, means forming upper and lower vertically spaced grinding stages, means for gravitally feeding material to be pulverized successively to said upper and lower grinding stages, and means for directing a stream of scavenging air through the stream of material during its passage from said upper stage to said lower stage. y

14. In an air-swept grinding mill, means forming upper and lower grinding stages, means for feeding material to be pulverized successively to said upper and lower grinding stages, means'for directing a stream of scavenging air through the stream of material during its passage from said upper stage to said lower stage, and means at the discharge side of said upper stage for restricting the flow of material to said lower stage.

15. In an air-swept grinding mill, a plurality of grinding rings and upper and lower circular rows of rolling grinding elements cooperating therewith to form upper and lower grinding stages, means for feeding material to be pulverized successively to said upper and lower grinding stages, and means for directing a stream of scavenging air through the stream of material during its passage from said upper stage to said lower stage.

16. In an air-swept grinding mill, a casing enclosing upper and lowergrinding rings and a circular row of rolling grinding elements positioned therebetween and cooperating therewith to form a grinding stage, said upper ring having air ports formed therein means for feeding material to be pulverized downwardly through said casing to one side of said row of grinding elements, and means for directing a stream of air past the opposite side of said row of grinding elements and upwardly in said casing through said air ports and then through the stream of material passing to said grinding elements.

17. A revoluble grinding ring for an air-swept pulverizing mill having grinding tracks formed on the upper and lower annular surfaces thereof, and a circular series of ports for the outward passage of material-laden air formed in a portion of said ring intermediate said grinding tracks, each port having a cross-sectional area tapering outwardly from its inner end to its outer end.

18. A revoluble grinding ring for an air-swept pulverizing mill having a grinding track formed on the lower annular surface thereof, and partition walls forming a series of ports for the outward passage of material-laden air in an intermediate portion of said ring above said grinding tracks, said partition walls being arranged at an oblique angle to the inner and outer peripheries of said ring and with their outer ends trailing their inner ends relative to the intended direction of rotation of said ring.

19. In an air-swept grinding mill, a casing enclosing a lower grinding ring, a circular row of rolling grinding elements in contact with said ring, and an upper driving ring in contact with said grinding elements, s aid driving ring being provided with a. series of ports for the passage of material-laden air, means for feeding material to be pulverzed to the outer side of said row of grinding elements; and means for directing a stream of air upwardly through said casing and mainly past the inner side of said row of grinding elements and then outwardly through said ports.

20. In an air-swept grinding mill, a substantially air-tight casing having an outlet for pulverized material in the upper part thereof and enclosing spaced grinding rings and'a circular row of rolling grinding elements positioned therebetween and cooperating therewith to form a grinding stage, one of'said rings having air ports formed therein, means for feeding material to be pulverized to one side of said row of grinding elements, and means arranged to direct a stream of air adjacent to and past the opposite 'side of said row of grinding elements to pick up material leaving said grinding stage and convey said material through said air ports and towards said casing outlet.

21. In an` air-swept grinding mill, a substantially air-tight casing having an outlet for pulverized material in the upper part thereof and enclosing spaced grinding rings and a circular row of rolling grinding elements positioned therebetween and cooperating therewith to form a grinding stage, one of said rings being rotatable and having air ports formed therein, means for feeding material to be pulverized to one side of said row of grinding elements, and means arranged to direct an annular stream of air adjacent to and past the opposite side of said row of grinding elements to pick up material leaving said grinding stage and convey said material through said air ports towards said casing outlet.

22. In an air-swept grinding mill, a substantially air-tight casing having an outlet for pulverized material in the upper part thereof and enclosing spaced grinding rings and a circular row of rolling grinding elements positioned therebetween and cooperating therewith to form a grinding stage, means for feeding material to be pulverized to one side of said row of grinding lelements, one of said rings having air ports associated therewith opening to a space communicating directly with the feed side of said row of elements, and means arranged to direct a stream of air adjacent to and past the opposite side of said row of grinding elements to pick up material leaving said grinding stage and convey said material through said air ports to permit the gravity return of any material separating out of the air stream in said space to the feed side of said row of grinding elements.

23. In an air-swept grinding mill, a substantially air-tight casing having an outlet for pulverized material in the upper part thereof and enclosing upper and lower grinding rings and a circular row of rolling grinding elements positioned therebetween and cooperating therewith to form a grinding stage, means for feeding material to be pulverized to one side of said row of grinding elements, said upper ring having air ports associated therewith opening to a space communicating directly with the feed side of said row of grinding elements, and means arranged to direct an annular stream of air at a relatively high velocity adjacent to and mainly past the opposite side of said row of grinding elements to pick up material leaving said grinding stage and convey said material` through said air ports and at a lower velocity through said space to permit the gravity return of any material separating out of the air stream in said space to the feed side of said row of grinding elements.

24. In an air-swept grinding mill having a substantially air-tight casing enclosing vertically spaced upper, intermediate, and lower grinding rings, circular rows of rolling grinding elements positioned between said upper and intermediate and said intermediate and lower grinding rings and cooperating therewith to form upper and lower grinding stages respectively, each arranged to receive material to b'e pulverized at one side of said row of elements and to discharge pulverized material at the other side, a series of ports extending through said intermediate ring, and

vmeans arranged to direct a stream of air adjacent to and past the discharge side of said lower row of grinding elements to pick up material pulverized in said lower grinding stage and then through said air ports to said casing outlet.

25. In an air-swept grinding mill having a substantially air-tight casing enclosing vertically spaced upper, intermediate, and lower grinding rings, circular rows of rolling grinding elements positioned between said upper and intermediate and said intermediate and lower grinding rings and cooperating therewith to form upper and lower grinding stages respectively, each arranged to receive material to be pulverized at one side of said row of elements and to discharge pulverized material at the other side, a series of ports extending through said intermediate ring communicating at their outlet ends with the inlet# side of said lower row of grinding elements, and means arranged to direct an annular stream of air adjacent to and mainly past the discharge side of said lower row of grinding elements to pick up material pulverized in said lower grinding stage and then through said air ports and upwardly to said casing outlet.

26. An air-swept pulverizing mill having an annular air-box, a mill casing having a material outlet opening formed therein, a stationary lower grinding ring mounted within said casing, a circular row of rolling grinding elements supported on said lower ring, a rotary upper grinding ring supported on said elements, a drive shaft extending upwardly axially of said row of elements and having a drive connection with said'upper ring, means for applying a grinding pressure between said elements and rings, means for feeding material to be ground to the outer side of said row of elements, means for directing an air blast from said air box upwardly past the inner side of said row of elements to remove pulverized material, and a series of ports formed in said upper ring for the outward iiow of materialladen air towards said material outlet opening.

ERVIN G. BAILEY.

PERRY R. CASSIDY. RALPH M. HARDGROVE.

CERTIFICATE OF CORRECTION.

Patent No. 2,012,266.

ERVIN G. BAILEY. ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, line 10, claim 4, for the word "balls" read elements; and that the said Letters Patent should -be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 18th day vof August, A. D. 1936.

Henry Van Arsdale (Seal) Acting Commissioner of Patents.

August 27, 1935. 

